LeetCode每日一题 19. 删除链表的倒数第N个节点

题目链接

思路

双指针，保持两个指针距离为n。引入头节点方便统一处理。

class Solution {
public:
    ListNode* removeNthFromEnd(ListNode* head, int n) {
        ListNode *dummy = new ListNode(0, head);
        ListNode* L = dummy, *R = head;
        for (int i = 0; i < n; ++i) R = R->next;
        while (R) {
            R = R->next;
            L = L->next;
        }

        L->next = L->next->next;
        return dummy->next;;
    }
};